Simple BGP with two operators, one advertisement and prepending

[Wojciech Bajorek]

Thanks, you might be right, indeed rp_filter was enabled.

I will test it today and see if it helps.

Does it mean that my config is just fine?

Regards,
Wojciech Bajorek

2017-04-25 12:36 GMT+02:00 Andrew <nitr0 at seti.kr.ua>:

> Maybe you forgot to disable rp_filter on uplink ifaces?
>
> And prepend works for incoming traffic, for outgoing - there is localpref.
> So, if outgoing traffic goes via ISP2 and incoming passed via ISP1 - it's
> dropped if rp_filter is enabled.
>
>
> On 25.04.2017 10:36, Wojciech Bajorek wrote:
>
> Hi,
>
> I have a pretty simple BGP configuration with two ISP and one static
> subnet to advertise.
> There is also one prepending configured but I'm not sure if it's working.
>
> The thing is that for some reason when I connect both ISP peers, traffic
> to the advertised ISP#2 networks (with shorter path) stops working after a
> couple of seconds. Tracert shows the last hop as ISP#2 border router.
>
> Similar configuration on Juniper router works without any problem, so I'm
> afraid that there is an error within my Bird config.
> Can you please help me out?
>
> PS. Without prepending situation is exactly the same.
>
> OS: Debian 8
> Bird: 1.4.5-1+deb8u1
>
>
> router id 90.90.90.1;
>
> protocol kernel {
>         persist;
>         scan time 15;
>         import all;
>         export all;
> }
>
> protocol device {
>         scan time 10;
> }
>
> filter bgp_isp1_out {
>         if net = 90.90.90.0/24 then
>         {
>                 accept;
>         }
>         else reject;
> }
>
> filter bgp_isp2_out {
>         if net = 90.90.90.0/24 then
>         {
>                 bgp_path.prepend(12345);
>                 bgp_path.prepend(12345);
>                 accept;
>         }
>         else reject;
> }
>
> protocol bgp bgp_isp1 {
>         import all;
>         export filter bgp_isp1_out;
>
>         local as 12345;
>         neighbor 2.3.4.5 as 2345;
> }
>
> protocol bgp bgp_isp2 {
>         import all;
>         export filter bgp_isp2_out;
>
>         local as 12345;
>         neighbor 3.4.5.6 as 3456;
> }
>
>
> Thank you.
>
> Regards,
> Wojciech Bajorek
>
>
>
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